False twisting apparatus

ABSTRACT

In combination with means to transport a continuous mono- or multi-filament thread in a linear thread path at a controlled rate of withdrawal, a frictional false twist device consisting of a single freely rotatable roller positioned obliquely to the linear thread path to receive a spiral loop of thread therearound, the freely rotatable roller having a concave arcuate thread contacting surface which is a surface of revolution.

United States Patent Hess et a1.

[ 51 Aug. 1,1972

[54] FALSE TWISTING APPARATUS [72] Inventors: Rudolf Hess, Elsenfeld;Heinz Engel, Kelsterbach/Main, both of Germany [73] Assignee: AkzonaIncorporated, Asheville,

22] Filed: Oct. 26, 1970 21 Appl. No.: 83,894

[30] Foreign Application Priority Data Oct. 29, 1969 Germany ..G 69 41966.5

[52] US. Cl. ..57/34 HS, 57/77.3, 57/77.4 [51] Int. Cl. ..D02g l/04 [58]Field of Search..57/34 R, 34 HS, 51, 51.6, 77.3, 57/77.4, 156, 157

[56] References Cited UNITED STATES PATENTS 2,410,419 11/1946 Bellezza..57/77.4

2,718,111 9/1955 Brown ..57/77.4 3,026,668 3/1962 Latimer ..57/77.43,470,583 10/1969 Denyes et al ..57/77.3 X 3,559,391 2/1971 Rice..57/77.4 X

Primary Examiner-Donald E. Watkins Attorney-Johnston, Root, OKeefe,Keil, Thompson & Shurtleff 5 7] ABSTRACT In combination with means totransport a continuous monoor multi-filament thread in a linear threadpath at a controlled rate of withdrawal, a frictional false twist deviceconsisting of a single freely rotatable roller positioned obliquely tothe linear thread path to receive a spiral loop of thread therearound,the freely rotatable roller having a concave arcuate thread contactingsurface which is a surface of revolution.

10 Claims, 4 Drawing Figures FALSE TWISTING APPARATUS To crimp man-mademonofilamentsor man-made continuous multifilament yarns as defined inthe German Industrial Standards, DIN 60001 (September, 1964), page 4,paragraph No. 2, it is common practice to subject them to afalse-twisting treatment, i.e., to pass them over or through a heaterand then through a cooling or fixing zone to a false-twisting means andfinally to a take-up spool. The twist producedby the.

falsetwisting means is carried back against the direction of threadtravel through the heating means up to a twist-stopper. In this way, thelargely plasticized or softened filament or multifilament thread passingthe heater has the opportunity to twist and, as it passes through thecooling zone between the heater and the false-twister, the twist isfixed in it. Twisting back to the zero point, i.e., zero-twist, isachieved by the rotation of the filament or' thread as it passes thetwisting unit, usually by means of a so-called twist-trapper.Accordingly, the filament thus treated and then collected or wound on atake-up spool does not have a genuine twist, but merely a tendency torotate when it is off-,

wound and relaxed.

Typical false-twist devices for imparting a durable torque-crimp tothreads or yarns of a fibrous synthetic thermoplastic polymer aredisclosed in a detailed explanation of the torque-crimp process setforth in Woven Stretch and Textured Fabrics by Hathome, John Wiley &Sons 1964), Chapter 2. Attention is also directed to US. Pat. No.2,803,109 for this description" of the originally developed false-twistprocess.

In this very widely adopted texturizing process, it is furtherknown-that a continuous monofilament or continuous multifilament threador yarn can be permitted to travel over a twisting means including arotatable roller arranged obliquely to the direction in whichthe threador yarn is traveling, cf., German Utility Model No. 1,898,540 and US.Pat. No. 2,946,181. The principle on which so-called frictionfalse-twisters" of this kind are based is that the filaments runningobliquely onto the surface of the twister (which is generally positivelydriven although in some cases it may be freely rotatable), show atendency to wander from their position relative to the twister, but arerolled back into their original position both by the tension inherent inthe filament or thread and also by the friction between filament andtwister. Known rollers for such frictional twistersare in the form oftruncated cones (US. Pat. No. 2,946,181) or cylinders (German UtilityModel No. 1,898,540). The disadvantage of cylinders is that severalrollers arranged parallel to or perpendicularly of one another areusually required for guiding the filaments in a satisfactory manner.These known falsetwist devices in which the monofilament or thread islooped at least partly around the twister, are unable to operate withoutyarn or thread guides before and/or after the twisters. Anotherdisadvantage of these known twisters resides in the twist slippage whichoccurs in contrast to more conventional false-twist spindles, e.g.,small tubes equipped with a twist-trapping pin, a'ndthe false-twistingis subject to wide fluctuations. Hitherto, it has only been possible toreduce these fluctuations by arranging several rollers one behind theother.

One, object of the present invention is to provide a frictionalfalse-twist device which does not exhibit any of the disadvantages ofconventional false-twisters, i.e., uncontrollable slip, the need toprovide several identical rollers and/or the need for yarn guides. Afurther object of the invention is to provide a false-twist device whichmakes it possible to work at much higher takeoff rates than was possiblewith conventional twisters of the frictional type referred to above,especially in drawtwist apparatus employing a false-twister. Take-offrates of more than 800 m/min. are now possible, being accompanied bystretching, whereas previous take-off rates were limited to about 400m/min. Another object of the inventionis to provide a false-twist devicewhich has a sufficiently high static friction even though looping is notmuch in excess of 360, i.e., using approximately one turn or spiral looparound the false-twister.

These and other objects and advantages of the invention will become moreapparent upon consideration of the following detailed disclosure.

It has now been found, in accordance with the invention, that especiallyuseful and advantageous results I can be achieved in a false-twistapparatus for the treatment of a continuous monofilament ormultifilament thread, especially for texturizing the thread with aheatset durable torque crimp, by employing apparatus which comprisesmeans to transport the thread in a substantially linear path includingmeans for withdrawing the thread from a feed source at a constant rate,and a frictional false-twist device consisting of a single freelyrotatable roller arranged with its axis of rotation obliquely to thelinear thread path in order to receive a thread contact surface ispreferably an arcuate surface mounting the roller on ball bearings,roller bearings or the like such that it can be easily turned by afilament or thread looped around the roller under tension and taken offat a constant speed, i.e., at a constant winding or withdrawal speed. Inother words, the roller must be rotated by the thread without having tobe positively driven by an auxiliary motor or other positive drivemeans.

. The false-twist device-employed in the apparatus of the inventionconsists of only a single roller because by virtue of the geometry ofthis roller, there is no need for one or more auxiliary rollers, threadguides or other means for improving the false-twisting action andguiding of the thread.

The term thread contact surface is employed herein to designate thatpart of the roller circumferential surface which comes into contact withthe transported monofilament or continuous multifilament thread throughlooping approximately once'around the roller. According to theinvention,it is this yarn contact surface which is concave with a smoothcurved or arcuate shapeand represents a surface of revolution, i.e., a

the yarn contact surface of the roller is a surface of revolutiongenerated by rotation of an are symmetrical with respect to thecenterline perpendicular of the axis of rotation of the roller, aboutthe axis of rotation, is particularly easy to manufacture and at thesame time particularly suitable for uniformly texturizing monofilamentsand continuous multifilament threads or yarns- To obtain especiallyuniform friction conditions between the filament or thread and thethread contact surface, it is of advantage for this contact surface tobe roughened to a depth (R,) of from about 2 to 8 microns (cf. GermanIndustrial Standards, DIN 4762, Sheet 1). The yarn contact surface ispreferably given a hard dull chrome finish for the same reasons.

The invention is also described by way of example with reference to theaccompanying drawings, wherein:

FIG. 1 is a largely schematic view of draw-twist apparatus illustratingthe path followed by the thread as it islooped around a twisteraccording to the invention;

FIG. 2 is a longitudinal section through a false-twist roller accordingto the invention together with its mounting for free rotation on a fixedspindle.

FIGS. 3 and 4 are plan views of two difierently mounted false-twistdevices according to the invention in which the thread contact angle,i.e., the oblique angle between the thread and the false-twist roller ismade variable by adjustably arranging and fixing the spindle indifferent positions.

In FIG. .1, the roller 1 acting as the false-twist device is arrangedbetween a heated fixing pin '14 and a stretching godet with its adjacentguide roller 15a of an otherwise conventional draw-twisting machine.Betweenthe fixing pin 14 and the roller 1, there must be a sufficientlylongcooling zone to ensure a heatsetting or fixing time suitable for thewithdrawal rate of the false-twistedfilament or thread 16. The pathfollowed by the filament or thread extends from the delivery spool orbobbin 12, over the guide pin 13, partly around the fixing pin 14, oncearound the roller 1 and then with several loops around the stretchinggodet assembly 15 and 15a, as shown by a continuous a heating plate, anelongated heating tube providing a contact and/or radiant heater or thelike.

A number of variations can be made in the specific draw-twist apparatusshown in FIG. 1 provided that one retains the essential freely rotatablefalse-twist roller 1 with its correct position in a linear transportedpath between feed means and withdrawal means. For example, the supplypackage or bobbin 12 can be of any conventional form and one can employa set of feed rolls to more carefully control the rate of feed as wellas inserting various types of tensioning means as the thread is broughtinto a linear path leading to the false-twist roller. Likewise, otherwithdrawal means may be employed although the godet and guide rollerassembly has been found to be especially advantageous. In order toachieve a uniformly false-twisted filament or thread, it is desirable tomaintain av substantially constant tension and a substantially constantlinear velocity of the thread as it is withdrawn in its linear pathinterrupted only by the loop around the false-twist roller.

It is a particularadvantage of the invention that the single freelyrotatable roller does not require supplemental guides, rollers,motor-driven spindles, twisttrappers or similar elements in order tofunction properly as a false-twist device. This means that the threadcan be transported directly from the heating means or other feed pointat which the backed up twist is stopped up to the false-twist roller,and likewise that the thread can than be conducted directly to thewithdrawal means, The term directly is used here in I the sense that thethread is conducted in a substantially broken line. Instead of theheated fixing pin 14, it is linear free path without any contact withother threading elements such as guides, rollers or the like.

FIG. 2 provides details of one preferred embodiment of the frictionalfalse-twist roller according to the invention. The roller V1 with itsarcuate concave thread contact surface is mounted on roller bearings 7so as to be freely rotatable on a spindle 2. A bushing 3 and rings 6 and8 prevent the roller from being axially displaced. Discs 4 and 5 aredesigned to prevent dirt from getting into the bearings. The roller 1shown in FIG. 2 has a concave yarn contact surface 9 which is in theform of a surface of revolution generated by the rotation of an areabout the axis of rotation ll,"this are which is also identified by 9being symmetrical with respect to a perpendicular line 10 passingthrough the center of the axis of rotation 11 of the roller 1.

FIG. 3 illustratesa false-twist roller with a variable or adjustablecontact angle. Coming from the heating plate as in FIG. 1, a thread 16passes the roller 1 and at the same time'is looped about once around itand then, while being false-twisted, continues traveling to thestretching godet and guide roller assembly. (The remaining apparatus hasbeen omitted since it either corresponds to FIG. 1 or may include otherconventional apparatus such as a take-up spool or the like.) Similarlyto the arrangement shown in FIG. 2, the roller 1 is mounted for freerotationby means of roller hearings on a fixed spindle attached to anL-shaped support 17. The leg 17a of this support 17 is spaced backwardlyfrom the roller 1 and is pivotally mounted for rotation to a supportingplate or frame 19 at the center of rotation 18 by means of a suitablelocking screw. At the free end of the roller support 17,- there arereference marks 21 which indicates the thread delivery, the angle ofcontact can be easily measured with a conventional protractor or othertool.

The device according to the invention is particularly suitable fortexturizing monofilaments and continuous threads having only two orthree individual filaments.

Polyamide threads, i.e., nylon threads, having a denier or size of dtexl4f2, dtex 22f l, dtex 22f2 and dtex 22 f 3, have been successfullyfalse-twisted and tests with deniers of dtex 50 have also beensuccessfully conducted as have tests with other fibrous polymers, for

example polyesters such as polyethylene terephthalate. (The total yarnsize is measured as dtex" preceding I -the value given while f precedesthe number of individual filaments in the thread.)

The false-twist roller of the invention in combination with otherconventional thread transporting apparatus and especially in a so-calleddraw-twist or stretch-twist machine permits very high speed operationwith a corresponding improvement in production capacity. The false-twistroller itself is light in weight and easily constructed so that it willrotate freely at high speeds in frictional contact with the runningthread. With a relatively long free path of the thread both before andafter the false-twist roller, there are no other parts or threadcontacting elements which can interfere with the smooth and trouble-freeoperation of the single roller. Moreover, the rotational velocity of theroller according to the invention is self-regulating and there is aminimum of thread slippage or loss of twisting so that very uniformlytexturized filaments or threads can be obtained when processingpreferred synthetic thermoplastic fibrous polymer filaments in anotherwise conventional manner.

The invention is herebyclaimed as follows: 1. F alse-twist apparatus forthe threatment of a continuous monofilament or multifilament threadcomposed of a linear fibrous high molecular weight polymer whichapparatus comprises:

means to transport said thread in a substantially linear path includingmeans to withdraw said thread from a feed source at a controlled rate;and

' a frictional false-twist device consisting of a single freelyrotatable roller arranged with its axis of rotation obliquely to saidlinear thread path in order to receive said thread in a single spiralloop therearound, said freely rotatable roller having a concave threadcontact surface which is a surface of revolution.

2. False-twist apparatus as claimed in claim 1 wherein said concavethread contact surface of said freely rotatable roller is an arcuatesurface symmetrical with respect to a plane perpendicular to the rolleraxis of rotation at the center of said roller axis.

3. False-twist apparatus as claimed in claim 1 wherein the threadcontact surface is roughened to a de th f about2to8microns.

alse-twist apparatus as claimed in claim 1 wherein aid thread contactsurface has a hard dull chrome finish.

5. False-twist apparatus as claimed in claim 2 whereinthe thread contactsurface is roughened to a depth of about 2 to 8 microns andhas a harddull chrome finish.

6. False-twist apparatus as claimed in claim 1 wherein said threadwithdrawal means is a stretching godet and guide roller assemblyarranged to receive said thread directly from said freely rotatableroller.

7. False-twist apparatus as claimed in claim 1 including heating meansfor heating said thread as it is transported in said linear thread pathleading up to said freely rotatable roller, said heating means beingseparated from said freely rotatable roller'by a distance sufficient topermit cooling of the thread and fixation of the twist wherein saidheating means is arranged to transport the thread directly therefrom insaid linear path to said freely rotatable roller and said threadwithdrawal means is arranged to receive said thread directly in saidlinear path from said freely rotatable roller.

10. False-twist apparatus as claimed in claim 9 wherein said threadwithdrawal means is a stretching godet and guide roller assembly.

W105 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION v 7 PatentNo. 1680 502 Dated v mag mg J I 1912 Inv'entor(a) Hess et a1 It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 5; line 45 "threatment" should read treatment .1

Signed and sealed this 12th day'of-Deoember 1972.

(SEAL) Attest:

EDWARD'M.FLETCHER,JR. ROBERT GOTTTSCHALK Attestlng Officer Commissionerof Patents

1. False-twist apparatus for the threatment of a continuous monofilamentor multifilament thread composed of a linear fibrous high molecularweight polymer, which apparatus comprises: means to transport saidthread in a substantially linear path including means to withdraw saidthread from a feed source at a controlled rate; and a frictionalfalse-twist device consisting of a single freely rotatable rollerarranged with its axis of rotation obliquely to said linear thread pathin order to receive said thread in a single spiral loop therearound,said freely rotatable roller having a concave thread contact surfacewhich is a surface of revolution.
 2. False-twist apparatus as claimed inclaim 1 wherein said concave thread contact surface of said freelyrotatable roller is an arcuate surface symmetrical with respect to aplane perpendicular to the roller axis of rotation at the center of saidroller axis.
 3. False-twist apparatus as claimed in claim 1 wherein thethread contact surface is roughened to a depth of about 2 to 8 microns.4. False-twist apparatus as claimed in claim 1 wherein aid threadcontact surface has a hard dull chrome finish.
 5. False-twist apparatusas claimed in claim 2 wherein the thread contact surface is roughened toa depth of about 2 to 8 microns and has a hard dull chrome finish. 6.False-twist apparatus as claimed in claim 1 wherein said threadwithdrawal means is a stretching godet and guide roller assemblyarranged to receive said thread directly from said freely rotatableroller.
 7. False-twist apparatus as claimed in claim 1 including heatingmeans for heating said thread as it is transported in said linear threadpath leading up to said freely rotatable roller, said heating meansbeing separated from said freely rotatable roller by a distancesufficient to permit cooling of the thread and fixation of the twistimparted thereto.
 8. False-twist apparatus as claimed in claim 7 whereinsaid heating means is a heated pin at the beginning of said linearthread path leading up to said freely rotatable roller.
 9. False-twistapparatus as claimed in claim 7 wherein said heating means is arrangedto transport the thread directly therefrom in said linear path to saidfreely rotatable roller and said thread withdrawal means is arranged toreceive said thread directly in said linear path from said freelyrotatable roller.
 10. False-twist apparatus as claimed in claim 9wherein said thread withdrawal means is a stretching godet and guiderolleR assembly.